Mechanism for boring compressor chambers for refrigerators



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MECHANISM FOR BORING I Filed Dec. 22, 1939 6 Sheets-Sheet l INVEN TOR.

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Aug. 12, 1941.

F. l. RATAICZAK MECHANISM FOR BORING COMPRESSOR CHAMBERS FOR REFRIGERATORS Filed Dec. 22, 19:59

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6 Sheets-Sheet 3 F. l. RATAICZAK Aug. 12, 1941.

MECHANISM FOR BORING COMPRESSOR CHAMBERS FOR REFRIGERATORS Filed Dec. 22, 1939 Aug. 12, 1941. F. l. RATAICZAK 2,252,203 MECHANISM FOR BORING COMPRESSOR CHAMBERS FOR REFRIGERATORS 6 Sheets-Sheet 5 NV ENT OR. lode/4. 1: B4 741C264 Filed Dec. 22, 1939 BY f HIS ATTORNEYS.

g- 12, 1941- F. l. RATAICZAK 2,252,203

MECHANISM FOR BORING COMPRESSOR CHAMBERS FOR REFRIGERATORS Filed Dec. 22, 1939 6 She'ets-Sheet 6 O INVENTOR.

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I"; ATTORNEYS.

Patentecl Aug. 12, 1 941 UNHTED 1 STATES PATENT OFFICE MECHANISM FOR BORING COMPRESSOR CHAMBERS FOR REFRIGERATORS Francis I. Rataiczak, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application December 22, 1939, Serial No. 310,595

6 Claims.

This invention relates to an apparatus for and method of forming a circular opening in a member which opening is irregular in cross-sectional contour or conforms to a limacon curve.

In compressors for refrigerating systems and particularly compressors of the type wherein a rotor, having a divider or vane of fixed over-all length extending through the rotor, is rotated within a circular refrigerant compression chamber about an axis that is offset relative to the axis of the chamber, the chamber must be slightly elongated or irregular in cross-sectional contour in order to permit the divider or vane to rotate along with the rotor therein. In this type of compressor the divider or vane slides through the axis of the rotor during rotation therewith and both ends of the divider or vane are adapted to engage the chamber wall throughout its circumference to divide the chamber, between its wall and the rotor, into compartments sealed from one another. In my copending application Serial No. 248,888, filed December 31, 1938, I have shown a compressor of the type described wherein two fixed length vanes or dividers slide back and forth within the rotor during rotation of the vanes and rotor within the refrigerant compression chamber. Previous methods of providing an irregular walled opening adapted to serve as a chamber for a compressor of this type have not been entirely satisfactory because the wall of the opening has not had a contour corresponding exactly to the path taken by the ends of the fixed length divider or vane. Consequently, the divider or vane has not sealingly engaged the wall of the chamber forming opening at all positions during rotation thereof within the chamber. Thus, refrigerant fluid trapped in one compartment, formed by the divider or vane between the rotor and wall of the chamber forming opening, has leaked past the divider or vane into the compartment on the other side thereof and rendered a compressor of the type described inefficient.

Therefore, an object of my invention is to provide an improved method of and. apparatus for forming an irregular-shaped, in cross-sectional contour, opening in a member and which opening is adapted to provide the refrigerant compression chamber of a compressor.

A further object of my invention is to provide a compression chamber of a refrigerant compressor with a circumference of a contour corresponding exactly to the path taken by the ends of a fixed length divider or vane in rotating with a rotor within the chamber and about an axis that is parallel with the axis of the chamber but offset relative thereto.

In carrying out the foregoing objects, it i a still further and more specific object of my invention to provide an improved apparatus that will bore an opening, having a cross-sectional contour corresponding to a limacon curve, in a member adapted to serve as the refrigerant compression' chamber of a compressor by providing the apparatus with a fixture which clamps the member to be operated upon tightly in place within the fixture against rotation relative thereto and which fixtur is constructed and arranged to permit placement of the member therein and quick and easy removal of th member therefrom.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

- Fig. 1 is a perspective view of a boring apparatus constructed in accordance with my invention;

Fig. 2 is an end View taken in the direction of the arrow 2 in Fig, 1 of a fixture device part of the apparatus;

Fig. 3 is a horizontal sectional view of the fixture device part of the apparatus taken on the line 33 of Fig. 2 showing the cutting or boring head thereof in a retreated position;

Fig. 4 is a vertical sectional view of the fixture device part of the apparatus taken on the line 4-4 of Fig. 2 showing the cutting or boring head thereof in an advanced position;

Fig. 5 is an enlarged cross-sectional View of the boring head part of the fixture device of the apparatus taken on the line 5-5 of Fig. 6;

Fig. 6 is an end view of the boring head disclosed in Fig. 5;

Fig. 7 is a view similar to Fig. 6 showing a quarter of a revolution of the boring head;

Fig. 8 is a view similar to Figs. 6 and 7 showing a half revolution of the boring head;

Fig. 9 is a view similar to Figs. 6, '7 and 8 showing three quarters of a revolution of the boring head;

Fig. 10 is a side view of the boring head taken on the line I0-| i] of Fig. 6 with parts thereof in section;

Fig. 11 is a vertical cross-sectional view of the boring head taken on the line Il-ll of Fig. 10;

Fig. 12 is a somewhat diagrammatic view corresponding to Fig, 6 to more clearly illustrate the present invention;

Figs. 13 to 18 inclusive are similar to Fig. 12 and illustrate positions of the slide and yoke in controlling th various locations of the cutting bit during rotation thereof to form one half of the irregular opening in the member to be bored; and

Fig. 19 is a view of the completed boring operation on a member and shows a rotor and vane located within the irregular opening thereof to represent a cross section of a refrigerant compressor.

Referring to the drawings and particularly to Fig. 1 thereof, I show one form of apparatus suitable for carrying out the invention and this apparatus includes a lathe having mounted thereon a fixture device 2| adapted to removably receive therein a member to be worked upon by the lathe and fixture device. The lathe may be of any suitable or conventional construction and includes a bed 22 having an apron 23' slidably mounted thereon and adapted to be moved back and forth upon the bed. The apron 23 carries or has integrally formed thereon a track-like upper portion 24 which receives the fixture device 2| and which permits movement of device 2| crosswise of bed 22 to align the device with the driven element or pintle of the lathe. A stationary gear box 25 located on one end of the lathe r has a driven pintle or element 26 projecting therefrom and connected to a round shaft 21 forming a part of device 2|. A screw shaft 26 extends from the gear box 25 and is threaded into the apron 23 so that rotation thereof by gears or the like within the box 25 causes the apron 23, track 24 and a part of device 2| to advance toward or move away from the stationary gear box end 25 of the lathe. Thus, the member to be worked upon and located within device 2| is provided with movement toward or away from the driving end of the lathe to complete a boring or other operation therethrough. The speed of advancement of device 2| toward the gear box 25 is adjusted or synchronized with respect to the speed of rotation of element or pintle 26 in accordance with the character of work to be performed on the member located within the work holding fixture device 2| on the lathe. Any suitable power means, such, for example, as an electric motor, may be employed for operating the gears and other elements within the gear box 25 of the lathe to rotate pintle 26 and screw shaft 28.

Referring now particularly to Figs. 2', 3 and 4 of the drawings, the work holding device 2| 1 mounted on track 24 of movable apron 23 of the lathe comprises a housing 3| provided with a horizontal base 32 having a track-like bottom, normally secured to the track 24, and a pair of integral vertically disposed outwardly extending ears 33. Housing 3| also comprises an integral elongated tubular bearing portion 34 having the round shaft 21 disposed therein. The one end of shaft 21 is rigidly secured, by a peg or the like 36, to the driven element or pintle26 of the lathe for rotation therewith (see Fig. 4) The other end of shaft 21 is hollowed out, as at 31 (see Fig. 3'), and receives a hollowed-out round tool holding shaft 38 which is secured thereto for rotation therewith by a key 39 and secured against lengthwise movement relative to the shaft 21 by a bolt 4|. Tool holding shaft 38 has a round boring head member or portion 42 and is adapted to be rotated along with shaft 21 by the lathe driving pintle or element 26. A yoke-like-casting 44 has it legs 45 washer 48.

abutting a finished end wall surface 46 on housing 3! and the legs are secured to housing 3| by bolts or the like 41. Each bolt 41 extends through a round hole 49 provided in the ears 33 of housing 3| and has a C-shaped washer 48 under the head thereof. Each bolt 41 passes through an opening provided in a bushing 56 located within the hole 49. Bushing 50 is of larger diameter than the head of bolt 41 and of smaller diameter than the diameter of the C-shaped The outer surface of the heads of bolts 41 is round and has a hexagonal-shaped hollowed out inner surface for the reception of a similarly shaped tool. Yoke casting 44 has a pin 5| stationarily secured thereto and projecting into the round head member 42 of the tool holding shaft 38 (see Figs. 3 and 5) for a purpose to be presently described. The center of guide pin 5| is parallel with but spaced a short distance from or is offset relative to the axis of rotation of tool holding shaft 38. The member to be operated on or bored by the apparatus and located within device 2| is in the present disclosure in the form of a collar-like member 53 having a rough or unfinished cylindrical inner wall. Instead of boring or cutting the hole in member 53 into a finished cylindrical inner wall form in cross-sectional contour it is, according to the present invention, desired to bore the inner wall of member 53 to provide the hole therein with a finished irregular cross-sectional contour corresponding to a limacon curve. The type of compressor to which collar-like member 53 is adapted to form a part necessitates this finished irregular circular crosssectional contour as before stated. Collar-like member 53, is secured to the finished vertical wall surface 46 of housing 3! by a plate 54 having an opening 55 therein which opening is slightly larger than the unfinished cylindrical opening in member 53. Bolts 56, each having a C-shaped washer 51 disposed under the heads thereof, pass through bushings located in holes provided in plate 54 at the corners thereof (see Fig. 2) and these bolts are threaded into housing 3|, as at 58 (see Fig. 1), to firmly clamp the collar-like member 53'onto or within device 2|.

The round head member or portion '42 of tool holding shaft 38 is cut out as at 6| (see Figs. 5 and 10) to provide spaced apart lips 62 (see Fig. 11) on the end thereof. Within cut-away part 6| of the head member or portion 42 of shaft 38 there is a yoke device 63, comprising plates 64 and 65 secured together by screws 66, adapted to slide back and forth between the lips 62. The shape-and fit of plates 64 and 65 together pro- 'Vides an opening 61' therebetween which extends entirely through yoke 63 and in which opening there is mounted a cross slide assembly 68 comprising plate 69 and 10, secured together by screws 1|, and having a felt washer 12 disposed in a groove provided in plate 63. The washer 12 surrounds the guide pin 5| and may be employed to absorb oil supplied to operating parts of the device 2|, for lubricating the round bearing surface of cross slide 66 with pin 5|. The cross slide assembly 68 surrounds and closely fits the guide pin 5| secured to yoke casting 44 and reciprocates within the opening 61 of the yoke device 63 when shaft 33 is rotated to thereby move the yoke device 63 within the cut-away part 6| and between the lips 62 of the head member 42. One side of plates 64 and 65, forming the yoke device 63, is hollowed out and receives a piece 14 (see Fig. 10) having a cutting bit or blade 15 formed integrally thereon (see Fig. 6). Piece 14 is clamped in.

place upon the yoke device 63 by a wedge block 75 (see Fig. 10) and screws 11 and 18. A cover plate 13 is secured to the end of head member or portion 42 of shaft 38 to prevent movement of the slide 53 and yoke 63 lengthwise relative to the head 42. Screws 8| pass through plate 19 and are threaded into the cars 62 of head 42.

In order to properly locate a collar-like member 53 in place within fixture device 2| so that it can be operated upon by the apparatus, yoke casting 44 and pin must be removed from housing 3|. The two bolts 41 are loosened and the c-shaped washers 48 removed therefrom, which then permits the bolts 41 and bushings 55 to be simultaneously withdrawn, during removal of yoke 44, through the openings 49. This clamping arrangement affords quick removal or replacement of the yoke casting 44. Plate 54 must also be removed in a similar manner to permit positioning of a member 53 in place within the device 2|. One end of a collar member 53 having a rough cylindrical inner surface is then placed against the surface 46 of housing 3|. The plate 54 is brought against the opposite end of mem ber 53 to hold the member against the surface 46 and the bolts 55 are threaded into housing 3| to temporarily clamp member 53 in place. A form or locating plate or plug 84, represented by the dot-dash line in Fig. 3, has a cylindrical outer surface concentric with a central hole therein and is used for a purpose to now be described. The pin 5| of yoke casting 44 is passed through the opening of the locating plate or plug 84 and the legs 45 of yoke 44 are brought into engagement with the ears 33. Plug 34 is moved into the member 53, while the member 53 is loosely clamped in device 2| by bolts 56, so that the cylindrical unfinished inner wall thereof is aligned with the pin 5| on yoke 44 or so that the unfinished cylindrical wall of member 53 will have the same axis as that of pin 5!. Bolts 41 are threaded into the yoke 44 and tightened to center the member 53 about the axis of pin 5| After the member 53 has been properly located within device 2|, with the aid of the locating plate or plug 34, the four bolts 55 are tightened to firmly clamp member 53in place against the finished surface 46 of housing 3|. The locating plug 84 must be removed from the device 2| prior to performing the boring operation on member 53. Therefore, yoke casting 44 and pin 5| carried thereby are again detached from device 2| to permit removal of the form plate or locating plug 84 from within member 53 and from pin 5|. Yoke casting 44 and pin 5| are thereafter replaced upon housing 3| and the bolts 41 drawn tight to firmly clamp same in place so thatpin 5| forms a guide means for the slide assembly 63 and yoke assembly 63. Thus, the axis of the cylindrical hole in member 53 is aligned with the axis of pin 5| but offset relative to the axis of shaft 33 and head member 42. During the operations described, the head 42 of tool carrying shaft 38 is located within the hollowed-out part of housing 3| as shown in Fig. 3 so that the same will not interfere with the positioning and clamping of member 53 in place.

With the member 53 firmly clamped in place within device 2| and with pin 5| extending through and snugly fitting the wall of the opening provided in cross slide assembly 63 the lathe is started into operation. The gears within gear box 25 are rotated to cause rotation of the lathe pintle or driven shaft 26 and also the screw shaft 28. The screw shaft 28 is threaded into the lathe apron 23, as before stated, and its rotation causes the apron to be moved toward the gear box end of the lathe to thereby cause engagement of the cutting bit or blade 15 with the inner cylindrical wall surface of member 53. The movement of apron 23 toward the gear box end of the lathe is, of course, calibrated in accordance with the depth of cutting to be carried out by the bit l5 during each revolution thereof and is also synchronized with the speed of rotation of the lathe pintle 25, controlling the speed of rotation of the bit or cutting blade. The axis of pin 5| and, consequently, the axis of the cylindrical inner surface of member 53 is offset relative to the axis of rotation of the tool holding shaft 33 in the manner previously described. Thus, when shaft 38 is rotated, the cross slide 63 within head member or portion 42 slides within the opening 61 of yoke device 63 and moves the yoke device within the cut-out part 6| of head 42 and relative to the lips 32. Such movement causes the bit or cutting blade 15 in rotating along with head 42 of shaft 38 to transcribe an irregular circular path. The arrangement and sliding connection of the various parts of the device and movement of blade 15 relative to the axis of head member 42 during rotation thereof causes the blade to cut a finished surface from the cylindrical inner wall of collar-like member 53, which finished surface conforms, in crosssectional contour, to a limacon curve. The irregularity of the opening 53 in the present disclosure deviates only by a few thousandths of an inch from a cylindrical opening. In Figs. 6, '7, 8 and 9, I have shown quarter turns respectively of a single revolution of the revolving tool-holding head 42 to illustrate the various sliding positions of the cross slide 58 within the yoke device 63 and of the yoke device within or relative to the cut-out part 6| of head 42 and to also illustrate movement of the cutting bit or blade 15 toward and/or away from the cylindrical outer surface of the head 42 of shaft 33. The revolving of head 42 and shaft 33 about one axis which is offset relative to the axis of guide pin 5| and, consequently, the axis of the hole in member 53 is, by sliding of the cross slide 68 and yoke 53 relative to one another, utilized to cause the bit or blade to gradually assume various positions away from or toward the axis of head 42 to thereby progressively cut the irregular or limacon curved finished inner wall surface in member 53.

Since the inner wall of the refrigerant compression forming chamber member 53 of the present disclosure deviates in its irregular contour only a few thousandths of an inch from a perfect circle, this deviation cannot be readily discerned from the drawings of the apparatus thus far described. Therefore, in Figs. 12 to 18 inclusive of the drawings, I have shown diagrammatically elements corresponding to the various elements of the apparatus and have exaggerated the distance between the axis of the cy 'ndrical opening in mel ber 53 or the axis of .in 55 and the axis of rotation of member 33 in order to more clearly illustrate the cutting or boring of the irregular or limacon curved inner wall surface of member 53. In Fig. 12, the position of shaft 33a and its head member or portion 42a. guide pin 5|a, cross slide 68a, yoke 53a; and cutting bit or blade 55a secured thereto corresponds to the position of the elements 33, 42, 5|, 58, 53 and 15 shown in Fig. 6. Member 530., which corresponds to member 53 in other drawings of the apparatus, is shown as having a cylindrical rough-cut opening 86 provided therein to illustrate the boring operation to be performed on member 53a. The cylindrical opening 86 has the same axis as pin 5m and, therefore, rotation of shaft 38a by the lathe is about an axis which is offset relative to the axis of pin 5i as before stated. Rotation of shaft 38a and its head 42a, upon engagement of the cutting bit kid with the end of member 53a, as shown in Fig. 12, causes cross slide 68a to tilt, yoke 63a to move further into slot Gia or further toward the center of shaft 380. to thereby rotate bit or blade 15a and make the initial cut 81 of a limacon curve in the cylindrical wall 86 as shown in Fig. 13. The initial cut 81 in Fig. 13 represents a 30 rotation of shaft 38a and its head 42a. In Fig. .14 the cut or bore 8'! of the limacon curve is extended by a 30 further rotation of shaft 38a and this cut is slightly and progressively deeper into member 53a than the initial cut. In Fig. 15 the shaft 38a and consequently head 42a has been rotated 90 to further extend and progressively deepen the cut or bore 8i. Fig. 16 represents a 120 rotation of shaft 38a and this further rotation of bit or blade 15a begins a shallower cut of the limacon curve in the member 53a. A 150 rotation of shaft 33a and a further rotating movement of bit or blade 2'5a.is represented in Fig. 1'7. A 180 rotation of shaft 38a and consequently head 42a is represented in Fig. 18 to complete one-half of a full rotation of the shaft 38a. Since the movements of the elements 38a, 5la,68a, 63a and 15a are duplicated in the remainder 180 rotation of shaft 38a and its head die, or, are in accordance with the movements illustrated in finishing the one side of the opening in member 53a, the opposite side thereof is, therefore, symmetrical therewith. Thus, the member 53 or 53a. has an opening therein which is irregular in cross-sectional contour or conforms to a limacon curve and provides a refrigerant compression chamber of the type described. In Fig. 19 I have shown the irregular opening in member 53 as being completed by continuous rotation of the cutting bit or blade 15 in the manner described and by moving the bit or blade through the member 53 by sliding the normally stationary parts of the fixture device 2! toward the gear box end of the lathe through the'intermediary of screw shaft 28 and apron 23. I also show in Fig. 19 a rotor 88 and a vane or divider 89 slidably mounted in the rotor and rotatable therewith to illustrate the type of compressor the irregular opening 8'! in member 53, which conforms to a limacon curve, is particularly applicable. The compressor shown in Fig. 19 is provided with a gas eous refrigerant inlet port 9i and a refrigerant outlet port 93 and the compressor, of course, would be provided with end plates for closing the chamber between the rotor 88 and wall 8?. The proportion of rotor 88 relative to the compression chamber and limacon curved wall 81 is exaggerated and is for illustrative purposes only in order that the widely spaced apart points of the axis of pin 5m relative to the axis of shaft 38a, as shown in Figs. 12 to 18 inclusive, may be utilized to more clearly show the invention. The

irregular opening 81 or its limacon curved wall tation thereof about the axis of rotor 88. Thus,

refrigerant drawn into a compressor of the type illustrated, by way of the port SH and. between the wall 8! and rotor 88, will be carried around the interior of member 53 by vane or divider 89 and compressed as it nears the outlet port 93 without leakage past the vane. The snug fit or contact of van-e or divider 89 with the limacon curved wall 8? during the entire revolution thereof within the irregular-shaped opening of member 53 provides an efhcient refrigerant compressor.

It will be apparent from the foregoing that I have provided an improved method of an apparatus for boring or cutting a finished chamber wall having an irregular cross-sectional contour. The method of holding the member to be bored and the method of transmitting a sliding motion to the cutter during rotation thereof provides an opening in the member having a cross-sectional contour conforming to a limacon curve which opening will insure uniform contact of a compressor vane or divider at all points around the circumference thereof during complete revolutions of the vane or divider within the opening and about an axis offset relative to the axis of the opening. Thus, the defects hereto pointed out with respect to other shaped openings and the inefficiency of a refrigerant compressor providcd with such an opening are eliminated by the irregular-shaped opening provided by the improved apparatus disclosed. By providing the apparatus with means for setting a member to be operated upon therein I eliminate the necessity of marking the limacon curve on each of such members and in this manner greatly facilitate the production of the members for the purpose specified.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: I

1. An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a revolving head member mounted within said device and movable relative thereto, a cutting blade rotatable with said head member and mounted thereon for movement perpendicularly relative to the axis of rotation thereof, guide means separate from said head member and stationarily mounted on said device, said guide means being offset with respect to the axis of said head member, means for rotating said head member and for causing other relative movement between said guide means and said head member, and means rotatable with said head member engaging said guide means and having a connection with said cutting blade to cause the blade to move toward and away from the axis of rotation of said head member for cutting an opening in the member adapted to be clamped to said device of greater dimension in one direction of cross-section through the center of said guide means than in another direction of cross-section therethrough.

2. An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a revolving head member mounted within said device and movable relative thereto, a cutting blade rotatable with said head member and mounted thereon for movement perpendicularly relative to the axis of rotation thereof, guide means separate from said head member and stationarily mounted on said device, said guide means being offset with respect to the axis of said head'me mber, means for rotating said head member and for causing other relative movement between said guide means and said head member, and means rotatable with said head member engaging said guide means and having a connection with said cutting blade to cause the blade to move toward and away from the axis of rotation of said head member for cutting an opening in the member adapted to be clamped to said device of a cross-sectional contour conforming to a limacon curve.

3. An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a revolving head member mounted within said device and movable relative thereto, a guide pin parallel to the axis of said head member but oiiset relative thereto, said pin being separate from said head member and stationarily mounted on said device, a cutting blade slidably connected to and rotatable with said head member and mounted thereon for movement perpendicularly relative to the axis of rotation thereof, means for rotating said head member and for causing other relative movement between said guide pin and said head member, and an element surrounding said guide pin and having a slidable connection with said cutting blade to cause the blade to move toward and away from the axis of rotation of said head member for cutting an opening in the member adapted to be clamped to said device of greater dimension in one direction of crosssection through the center of said guide pin than in another direction of cross-section therethrough.

4. An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a revolving head member mounted within said device and movable relative thereto, a guide pin parallel to the axis of said head member but offset relative thereto, said pin being separate from said head member and stationarily mounted on said device, a cutting blade slidably connected to and rotatable with said head member and mounted thereon for movement perpendicularly relative to the axis of rotation thereof, means for rotating said head member and for causing other relative movement between said guide pin and said head member, and an element surrounding said guide pin and having a slidable connection with said cutting blade to cause the blade to move toward and away from the axis of rotation of saidhead member for cutting an opening in the member adapted to be clamped to said device of a cross-sectional contour conforming to a limacon curve.

5. An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a hollow revolving head member mounted within said device and movable relative thereto, a guide pin within the hollowed out part of said head member, said pin being parallel to the axis of said head member but offset relative thereto, said guide pin being separate from said head member and stationarily mounted on said device, a cutting blade rotatable with said head member, holding means for said blade slidably connected to said head member for movement perpendicularly relative to the axis of rotation thereof, means for rotating said head member and for causing other relative movement between said guide pin and said head member, and an element surrounding said guide pin and having a sliding connection with said cutting blade holding means to cause the blade to move toward and away from the axis of rotation of said head member for cutting an opening in the member adapted to be clamped to said device of greater dimension in one direction of cross section through the center of said guide pin than in another direction of cross-section therethrough.

6, An apparatus of the class described comprising, a device adapted to have a member to be worked upon removably clamped thereto, a hollow revolving head member mounted within said device and movable relative thereto, a guide pin within the hollowed out part of said head member, said pin being parallel to the axis of said head member but offset relative thereto, said guide pin being separate from said head member and stationarily mounted on said device, a cutting blade rotatable with said head member, holding means for said blade slidably connected to said head member for movement perpendicularly relative to the axis of rotation thereof, means for rotating said head member and for causing other relative movement between said guide pin and said head member, and an element surrounding said guide pin and having a sliding connection with said cutting blade holding means to cause the blade to move toward and away from the axis of rotation of said head member for cutting an opening in the member adapted to be clamped to said device of a cross-sectional contour conforming to a limacon curve.

FRANCIS I. RATAICZAK; 

